Glycidyl acetate as viscosity modifier for liquid epoxy resins

ABSTRACT

A fluidized resinous composition comprising (1) a liquid epoxy resin and (2) glycidyl acetate as a viscosity control agent therefor. Also described are the cured products formed therefrom.

United States Patent 11 1 Stange' GLYCIDYL ACETATE AS VISCOSITY MODIFIER FOR LIQUID EPOXY RESINS US. Cl. ..-....260/30.4 E1 Int. Cl. ..C08g 51/32 Field of Search ..260/30.4 EP, 348 A References Cited UNITED STATES PATENTS 2,528,932 11/1950 w ilesetal. ..260/30.4 EPX 51 Jan. 30, 1973 FOREIGN PATENTS OR APPLICATIONS 983,5 l6 2/1965 Great Britain ..260/30.4 EP

Primary ExaminerLewis T. Jacobs Attorney-Robert D. Jackson, Eugene G. Seems and Pauline Newman [57] ABSTRACT A fluidized resinous composition comprising (1) a liquid epoxy resin and (2) glycidyl acetate as a viscosity control agent therefor. Also described are the cured products formed therefrom.

4 Claims; N0 Drawings GLYCIDYL ACETATE AS VISCOSITY MODIFIER FOR LIQUID EPOXY RESINS BACKGROUND OF THE INVENTION Epoxy resins are known substances usually formed by condensing an epichlohydrin with a compound containing active hydrogens. The polyhydric phenols are the most common in commercial practice. An especially important class of phenols contain a single carbon atom between the rings and are prepared from an react chemically and become part of the resin system.

methacrylate and the glycidyl ester of a higher tertiary carboxylic acid are among the more important members.

SUMMARY OF THE INVENTION It has now been discovered that excellent viscosity control in an epoxy resin system can be attained with glycidyl acetate and the provision of fluid epoxy resins containing same constitutes the principal object and purpose of the invention. Other objects and purposes will become manifest subsequently.

GENERAL DESCRIPTION AND PREFERRED EMBODIMENT(S) (s) In carrying out the invention, glycidyl acetate and the liquid epoxy resin are blended together and the resulting resin mixture retained until ready for curing. The amount of glycidyl acetate used is from about 1.0

aldehyde or ketone and a phenol having a free ortho or para portion. The compound, bisphenol A, having the structure M mm W CH3 and formed by condensing acetone with phenol is a well known commercial product from which epoxy resins are manufactured. For a fuller description of epoxy resins, reference is made to the familiar treatise by Henry Lee and Kris Neville entitled Hand book of Epoxy Resins (McGraw-Hill, Inc. 1967).

Glycidyl acetate is a known compound which can be prepared from ketene and glycidol.

Reference is now made to the following non-limiting examples.

EXAMPLE 1 A series of mixtures of glycidyl acetate and 100 parts of diglycidyl ether of bisphenol A (Araldite 6005) were prepared. The initial viscosities of the diglycidyl resin mixtures were measured with a Brookfield viscometer at 25C. The measured viscosities of the mixtures ranged between 81-00 centipoise for 0 glycidyl acetate to 248 centipoises for 25 percent. A clear fluid mixtures resulted from which air bubbles readily separated. To 100 grams of each mixture, about 14 gram of triethylenetetramine curing agent, was added and thoroughly mixed. The mixtures were poured into casting molds 8 inches X 8 inches X it inch thick and allowed to cure overnight at ambient temperature. The samples were then cured an additional 8 hours at 100C., cut into appropriate size for measurement of physical properties. Procedures described in ASTM D-638, D14 790 and D14 78 were used to measure tensile strength, flexural strength and Rockwell hardness, respectively. Improvements in tensile and flexure were noted with increase glycidyl acetate content. The test results are summarized in Table 1.

TABLE I [Araldite epoxy resin 6005 cured room temperature-overnight room temperature plus 8 hours at 100 C Tensile Flexure Gel Hardness, Brookfield time Stress Elong. Modulus Strength, Modulus, Rockwell Modifier Phr. viscosity (min.) (p.s.i.) (percent) (p.s.i.) p.s.l. (psi. M

Glyeldyl 0 8, 100 45 8, 776 1. 2 490, 000 10, 368 460, 000 112 5 3,220 87 8, 614 1.08 480,000 17,284 ,000 109 10 1,272 9,857 1.48 490, 000 17,163 470, 000 105 Acetate 15 682 80 8, 251 1. 01 510, 000 16, 926 470, 000 98 20 386 8, 622 1. 01 530, 000 17, 696 490, 000 103 25 248 10, 472 1. 530, 000 19, 584 530,000

" Diglycidol ether of bisphenol A, a product of Ciba Products Co.', epoxy equivalent weight=182189; viscosity, centipoises at percent to about 25.0 percent by weight based on the weight of resin. Commonly the concentration is about 10 percent.

The resin mixture is cured in the usual manner using known curing agents such as polyamines or polycarboxylic acid anhydrides.

EXAMPLE 2 Using the procedure of example 1, except the resin was the higher molecular weight (Araldite 6010) having an initial Brookfield viscosity of 15,680 centipoises. After mixing with diluent, the viscosities were reduced and at 25 percent glycidyl acetate the viscosity was 308 centipoises at 25C.

Physical properties of resin cured triethylenetetramine showed only slight lower tensiles but flexural strength was higher with 25 parts of diluent. The results are summarized in Table 11.

with

2. A composition according to claim 1 wherein the 1,2-epoxy resin is the diglycidyl ether of bisphenol A.

3. A composition according to claim 1 wherein the 1,2-epoxy resin has an epoxy equivalent weight of 5 185-196 and a viscosity in centipoises at 25 C. of from TABLE II [Araldlte epoxy resin 6010 cured room temperature-overnight room temperature plus 8 hours at 100 C.]

Tensile Flexure Hardness, Brookfield Gel time Stress Elong. Modulus Rockwell Modifier Phr. viscosity (min.) (p.s.i.) (percent) (p.s.i.) Strength Modulus M Glycidyl 15, 680 40 9, 710 1. 40 490, 000 12, 694 460, 000 11 2 4, 640 70 16, 680 440, 000 109 l, 668 67 7, 371 0. 86 520, 000 17, 460, 000 106 Acetate 15 840 60 7, 252 0. 84 620, 000 18, 076 470, 000 103 466 56 8, 533 1. 07 540, 000 18, 514 5,000,000 101 308 53 8, 143 0.84 650, 000 18, 508 5, 000,000 101 Diglycidol ether of bisphenol A (LR. No. 4-1-10), a product of Ciba Products 00.; epoxy equivlaent Weight=185196; viscosity,

centipoises at 25 C.=12 000-16 000 4. A composition according to claim 1 wherein the 1,2-epoxy resin has an epoxy equivalent weight of 182-189 and a viscosity in centipoises at 25 C. of from 7,000-l0,000. 

1. A fluid resinous composition comprising a 1,2-epoxy resin formed by condensing epichlorohydrin with a compound containing active hydrogen and as a viscosity control agent therefor, 1.0 percent to about 25 percent based on the weight of the resin of glycidyl acetate.
 2. A composition according to claim 1 wherein the 1,2-epoxy resin is the diglycidyl ether of bisphenol A.
 3. A composition according to claim 1 wherein the 1,2-epoxy resin has an epoxy equivalent weight of 185-196 and a viscosity in centipoises at 25* C. of from 1,200-1600. 